docs: fix preprocessors code example
docs: fix preprocessors code example

Closes #693

sublimino/karma,powerkid/karma,IveWong/karma,chrisirhc/karma,sylvain-hamel/karma,wesleycho/karma,WickyNilliams/karma,marcodejongh/karma,Dignifiedquire/karma,hexelon/karma,hexelon/karma,czchen/karma,kahwee/karma,tomkuk/karma,pmq20/karma,KrekkieD/karma,jeffjewiss/karma,rhlass/karma,vojtajina/karma,skycocker/karma,hitesh97/karma,lencioni/karma,stevemao/karma,unional/karma,rageshkrishna/karma,jacopotarantino/karma,codedogfish/karma,aiboy/karma,maksimr/karma,SamuelMarks/karma,stevemao/karma,unional/karma,viruschidai/karma,youprofit/karma,IsaacChapman/karma,maksimr/karma,skycocker/karma,johnjbarton/karma,ernsheong/karma,cironunes/karma,codedogfish/karma,tomkuk/karma,machuga/karma,yandex-lego/karma,IveWong/karma,youprofit/karma,jeffjewiss/karma,gdi2290/karma,clbond/karma,Dignifiedquire/karma,robdodson/karma,jjoos/karma,stevemao/karma,gayancliyanage/karma,growlybear/karma,jfroom/karma,Basemm/karma,astorije/karma,Basemm/karma,unional/karma,sja/karma,karma-runner/karma,nmalaguti/karma,simudream/karma,tomkuk/karma,brianmhunt/karma,xiaoking/karma,IveWong/karma,IsaacChapman/karma,wesleycho/karma,marcodejongh/karma,rgaskill/karma,dmitriiabramov/karma,buley/karma,simudream/karma,brenoc/karma,gayancliyanage/karma,lencioni/karma,powerkid/karma,bertrandgressier/karma,swayf/karma,astorije/karma,xiaoking/karma,drkibitz/karma,mprobst/karma,jamestalmage/karma,jjoos/karma,mprobst/karma,adamnation/karma,shirish87/karma,buley/karma,Klaudit/karma,rageshkrishna/karma,gdi2290/karma,igorlima/karma,peteryates/karma,david-garcia-nete/karma,wesleycho/karma,pmq20/karma,lgalfaso/karma,patrickporto/karma,jamestalmage/karma,chrisirhc/karma,panrafal/karma,matti/karma,machuga/karma,jan-molak/karma,marthinus-engelbrecht/karma,buley/karma,Dignifiedquire/karma,yandex-lego/karma,pedrotcaraujo/karma,rageshkrishna/karma,david-garcia-nete/karma,oyiptong/karma,hitesh97/karma,thirtyseven/karma,shirish87/karma,jeffjewiss/karma,johnjbarton/karma,powerkid/karma,chrisirhc/karma,sublimino/karma,fredrikbonander/karma,IveWong/karma,amagee/karma,panrafal/karma,hitesh97/karma,vtsvang/karma,brianmhunt/karma,dmitriiabramov/karma,oyiptong/karma,fredrikbonander/karma,ernsheong/karma,sylvain-hamel/karma,growlybear/karma,jamestalmage/karma,thirtyseven/karma,thomasboyt/karma,andersjanmyr/karma,pedrosnk/karma,oyiptong/karma,behzad88/karma,fivetanley/karma,vojtajina/karma,astorije/karma,behzad88/karma,dmitriiabramov/karma,kahwee/karma,lencioni/karma,timebackzhou/karma,brianmhunt/karma,OniOni/karma,r3mi/karma,rgaskill/karma,jjoos/karma,vtsvang/karma,lgalfaso/karma,Demeterr/karma,WickyNilliams/karma,swayf/karma,skycocker/karma,aiboy/karma,david-garcia-nete/karma,r3mi/karma,jsdir/karma,growlybear/karma,rgaskill/karma,hitesh97/karma,youprofit/karma,simudream/karma,patrickporto/karma,igorlima/karma,Dignifiedquire/karma,skycocker/karma,Sanjo/karma,fivetanley/karma,Klaudit/karma,simudream/karma,davidmichaelkarr/karma,thomasboyt/karma,Sanjo/karma,jsdir/karma,youprofit/karma,clbond/karma,bitwiseman/karma,Klaudit/karma,Demeterr/karma,aiboy/karma,oyiptong/karma,gayancliyanage/karma,czchen/karma,patrickporto/karma,SamuelMarks/karma,unional/karma,vojtajina/karma,eddiemonge/karma,mprobst/karma,brianmhunt/karma,IsaacChapman/karma,xiaoking/karma,karma-runner/karma,rhlass/karma,revolunet/karma,maksimr/karma,pmq20/karma,chrisirhc/karma,bitwiseman/karma,Sanjo/karma,cironunes/karma,andersjanmyr/karma,pedrosnk/karma,harme199497/karma,vtsvang/karma,aiboy/karma,bertrandgressier/karma,ijobling/karma,ijobling/karma,KrekkieD/karma,shirish87/karma,astorije/karma,rhlass/karma,amagee/karma,Klaudit/karma,codedogfish/karma,peteryates/karma,panrafal/karma,timebackzhou/karma,revolunet/karma,jamestalmage/karma,eddiemonge/karma,vtsvang/karma,nmalaguti/karma,jfroom/karma,jjoos/karma,bitwiseman/karma,adamnation/karma,kahwee/karma,OniOni/karma,timebackzhou/karma,drkibitz/karma,pedrotcaraujo/karma,IsaacChapman/karma,viruschidai/karma,pmq20/karma,KrekkieD/karma,powerkid/karma,SamuelMarks/karma,rhlass/karma,pedrotcaraujo/karma,patrickporto/karma,nmalaguti/karma,jan-molak/karma,clbond/karma,karma-runner/karma,marthinus-engelbrecht/karma,behzad88/karma,jsdir/karma,wesleycho/karma,gayancliyanage/karma,robdodson/karma,KrekkieD/karma,harme199497/karma,brenoc/karma,ijobling/karma,johnjbarton/karma,timebackzhou/karma,harme199497/karma,karma-runner/karma,davidmichaelkarr/karma,sylvain-hamel/karma,codedogfish/karma,Sanjo/karma,ernsheong/karma,harme199497/karma,buley/karma,clbond/karma,pedrotcaraujo/karma,tomkuk/karma,marthinus-engelbrecht/karma,pedrosnk/karma,marthinus-engelbrecht/karma,xiaoking/karma,adamnation/karma,jacopotarantino/karma,stevemao/karma,yandex-lego/karma,sja/karma,nmalaguti/karma,matti/karma,kahwee/karma,johnjbarton/karma